For example, a recent tour of Baltimore's art scene began quietly at 8:40 a.m. with just one car and six sleepy occupants. Eight hours later, the caravan that pulled up outside the Charles Village home of paper artist Cara Ober had grown to three vehicles containing at least 14 people, including four reporters and photographers.

The throng kept growing because Mera, who will permit herself to be addressed by no other name, embarks on off-the-wall adventures that also are lots of fun. On a late October weekend, she's visiting the studios of 37 Baltimore artists who were chosen by lottery from a pool of about 150. The whirlwind tour, which takes place in just 36 hours, was inspired by a similar marathon she conducted of Washington studios in 2009.

During her Baltimore visit, Mera was quietly evaluating the artists for inclusion in a group show she was arranging in a prestigious Manhattan gallery — though the painters and sculptors didn't know that yet. They thought they were being considered for "Select 2014," an exhibit sponsored by the Washington Project for the Arts that opens Feb. 27, and for which Mera is one of eight guest curators.

They were indeed being evaluated for the Northern Virginia show. But that wasn't the headline.

(Later, photographer Alessandra Torres would write in an email that upon receiving the phone call informing her that she was among the 19 artists selected for both shows, first she screamed, and then she started laughing. "The entire experience is like an art fairy tale," Torres wrote, "just like the movie version of 'Great Expectations.' ")

Not that the artists needed an incentive. They would gladly open their studios at any hour for the Rubells. Mera, her husband, Don, and their two grown children have put together what they describe as one of the largest private holdings of contemporary art in the world.

The couple began purchasing art in the mid-1960s when Mera was a Head Start teacher and Don was in medical school. They allocated 25 percent of Mera's then-weekly salary of $100 to buy original art — and still spend roughly the same proportion of their income on contemporary paintings and sculptures. They were among the earliest collectors of such future superstars as Jeff Koons, Cindy Sherman and Richard Prince. Now the Rubell Family Collection is housed in a 45,000-square-foot museum in Miami, and the couple divide their time between Florida and New York.

Mera's energy is irresistible. Arms akimbo, she enthuses past all obstacles. The cookies and pastries that artists put out for each 20-minute studio visit are abundant and homemade. They satisfy an appetite the visitors didn't even know they had — just like the art hanging on the studio walls.

Who wouldn't want to tag along?

Jane Deering, the owner of a California gallery bearing her name, is along on the tour … well, just because. "You are magical," she tells Mera. "You know how to put these artists right at ease."

"Oh, stop it," Mera replies.

Deering may be on to something. There's definitely a whiff of a modern-day fairy godmother about Mera — though this godmother sports a black Panama hat and pink-rimmed shades. She loves, loves artists and radiates excitement and pleasure when in their company.

"Wow!" she says after visiting Rachel Rotenberg's Northwest Baltimore studio and marveling at her muscular wood sculptures. "Oh, my God! That was some visit. People have no idea what's going on here in Baltimore."

An hour later, she's in Gary Kachadourian's studio across town, admiring his meticulous black-and-white, life-size drawings of humble objects. Kachadourian's posters, which begin at $6 for a sketch of a chicken bone lying on the sidewalk, bear out one of Mera's favorite sayings: "Everyone can afford to own an original work of art."

Impulsively, she breaks her own rule.

"This trip isn't supposed to be about buying," she says. "But I can't resist."

Mera opens up her wallet — and everyone else in the group scrambles to do the same.

But no one who has acquired the Rubells' reputation for discernment can afford to be uncritical. When Mera judges that the situation warrants tough love, she dispenses it.

For instance, she advises one artist to focus more on refining her vision and less on building an audience. "The journey to become a great artist is long," Mera says, "and it's still ahead of you."

But overall, Mera thinks Baltimore's art scene is an undiscovered treasure, and she thinks outsiders should know about it. When Mera gets a strong feeling that something should be done — and she has many, many such strong feelings — she acts. It takes her less than 72 hours after the tour ends to set up the show at Manhattan's Marianne Boesky gallery, which has a reputation for spotting up-and-coming artists on the verge of a breakthrough.

Mera knows people who know people. Her conversation includes anecdotes about Barbra Streisand (whom Mera met in a maternity ward as she was delivering her son), the filmmaker John Waters (they had lunch just the other day) and the Chinese dissident artist Ai Weiwei. Pop icon Andy Warhol was a close family friend.

But her greatest affinity isn't with the rich and famous; it's with struggling artists who, like her, have led a vagabond existence. As she tells Rotenberg:

"I grew up in a family where you put your belongings in a bundle on a stick."

Mera's family fled their native Poland in 1939 after her father came home one day from the front, where he was stationed with the Polish army. Because he was blond and blue-eyed, Mera says, no one knew he was Jewish. Mera's father convinced his wife and nine brothers and sisters that they had to leave the country that very night, before the Nazis crossed the Polish border.

He tried to persuade Mera's mother's family to come along. They demurred, reasoning that the Nazis wouldn't hurt mothers with young children.

"Two of them survived Auschwitz," Mera says. "Three did not."

Mera was born in 1943 in Tashkent, the capital city of what is now Uzbekistan, and spent her childhood in refugee camps in Russia and Germany. When she arrived in New York at age 12, she didn't know a word of English.

Of necessity, she began spending a lot of time in the library and proved to be a quick study, acquiring not just a fluency in English but an authentic New York accent to go with it. After enrolling in Brooklyn College to study psychology, she says, she began sitting at the same library table as an attractive medical student.

"For three months, this gorgeous guy sat across from me every day, and never said a word," she says. "Then, one day he asked me if I wanted to take a walk. I did, and the first words out of his mouth were, 'Will you marry me?' "

The couple collected art steadily while Don became a gynecologist and Mera got into commercial real estate. They raised two children: Jason, who works in the family business, and Jennifer, a New York-based artist whose portrait as a child was sketched by Warhol. Another close — and famous — family member was Donald's brother, Steve Rubell, who was best known for co-founding the discotheque Studio 54. Steve left his estate to Don and Mera when he died in 1989 of complications from AIDS.

In 1993, the couple transformed a former federal Drug Enforcement Administration warehouse in Miami into an art museum, and a few years later bought their first hotel. A pattern soon emerged: One of the Rubells would a venture into a new city while investigating a building purchase and begin championing the local arts community. Sometimes, as in Miami, it worked the other way around.

In Washington, for instance, the couple bought a former Best Western Hotel in 2002 and transformed it into the uber-hip Capital Skyline Hotel. For the past several years, they've been renovating a long-closed high school on the District of Columbia's southwest side into what will become a satellite museum for the Rubell Family Collection.

In Baltimore, the Rubells are in the midst of renovating the 85-year-old Lord Baltimore Hotel. Mera has big plans for both the hotel and local art community, and she unveils one of them during an impromptu bull session while visiting Ober's Charles Village studio.

Instead of a standard hotel gift shop, the Lord Baltimore may house a small gallery selling original works by local painters, ceramists, sculptors. It will be called "The Anyone Can Afford to Own an Original Work of Art Gift Shop."

But why stop there?

Someone suggests that the small refrigerators in each of the hotel's 440 rooms could contain original artworks instead of drinks.

Everyone laughs, and Mera runs with the idea:

"We could put a piece of art inside," she says — and it seems she's only partly joking. "You could buy it or not buy it. If it disappears from the room after you check out, it goes on your bill."

No bells and whistles went off today, but the Walters Arts Museum just won the distinction of providing the 10,000th entry in the World Digital Library, a Library of Congress project launched in 2009 that provides free Internet access to manuscripts, maps, books, works of art, photographs, films,...